The present invention relates to power plants and pertains particularly to a CFB boiler plant, with gas turbine utilizing sulfur containing fuels with emissions controlled by the CFB boiler.
There exists in the power generating industry a need for more efficient power plants for converting fossil fuels to electrical power. The most commonly used gas turbine power generation systems are fueled by premium fuels, like natural gas. However, the cost and uncertainty of the availability of premium fuels make premium fuel gas turbine power generating plants less desirable. The most efficient overall plant system is the combined cycle (gas and steam) system. Therefore, there also exists an even greater need for power plants capable of operating efficiently on lower grades of fuels that exist in abundance in many regions of the world.
Atmospheric pollution is of great concern throughout the world today. One of the major causes of atmospheric pollution is the burning of various fossil fuels for the generation of heat and power. Many fuels contain impurities, such as sulfur that is particularly noxious and polluting. Systems, including scrubbers, have been developed for removing these pollutants from exhaust gases of power plants. However, these systems are very expensive and frequently not cost effective, particularly for gas turbine power plants.
Circulating fluidized bed boilers have been developed for burning low quality coals for powering steam turbines. The circulating fluidized bed contains sorbents like limestone or dolomite, which remove sulfur compounds from the exhaust gases and provide a somewhat economical system.
Sulfur containing fuels can be used in powering gas turbine engines if cost effective means is available to reduce Sulfur Oxide (SOx) emissions from the exhaust. In gas turbine applications, the air quantity used is four to five times higher than conventional coal fired boilers. Therefore, the scrubber costs are also four to five times higher per KW output of the gas turbine. This makes the use of sulfur containing fuels in gas turbines uneconomical with present systems.
Applicant has discovered an arrangement whereby a gas turbine for burning sulfur containing fuels can be added to or combined with a circulating fluidized bed (CFB) boiler plant, with the CFB serving as a scrubber for the gas turbine exhaust and makes the combined system more efficient and cost effective.